Master2 internships from Grenoble University

 

During the past years, students from the Master-2 program of the Grenoble university have visited the 30m telescope to conduct short research projects. Since 2020, these projects are conducted under the guidance of Ana Lopez Sepulcre. Before, Bertrand Lefloch had been responsible.

Star formation is the key topic of these projects.

Since 2020, the projects focus on the Serpens South protocluster and the surrounding clouds. The emission of SiO and high-velocity CH3OH is mapped in the densest area of this young protocluster that is a promising yet poorly studied analogue of what must have been the formation environment of the Solar System. The aim of these observations is to locate and characterise, both kinematically and chemically, the jets and outflow shocks present in the region, and to compare their properties with those of well known but more isolated or loosely clustered sources such as L1157 and NGC 1333. The presence of methanol in molecular outflow shocks may indicate an underlying molecular complexity. Its detection is therefore an important first step that can lead to detailed follow up studies which will place valuable constraints on time-dependent astrochemical shock models and reaction networks.

Till 2019, the projects focussed on the following two topics: radiatively driven implosion, taking the Trifid Nebula M20 as example object, and molecular outflows in L1157 and Herbig-Haro objects.

I. The model of "Radiatively-Driven Implosion" (RDI) successfully accounts for the presence of long-lived molecular cores in the neighbourhood of young massive stars. RDI predicts that the stellar radiation drives the propagation of an ionization front preceded by a convergent shock front and a Photon-Dominated Region into the neutral gas. This scenario is actually incomplete as it neglects the formation of the dense structures in the parental clouds, before the onset of photoionization. The many Cometary Globules discovered in the young Trifid Nebula (M20) allow us to tackle these issues. We have mapped specific tracers of the molecular and PDR gas to investigate the dynamics of the interaction with the high-energy radiation field of the nebula.

II. The birth of protostars is accompanied by outflows, which interact through shocks with the parental cloud. The long studied chemically active outflow L1157 has become a benchmark for MHD shock model studies. Two molecular bowshocks, with dynamical timescales of 1000 and 2000 yrs, respectively, are symmetrically detected in each outflow lobe. The goal of the project is to investigate the chemical richness produced in these outflow shocks and compare the chemical diversity under different range of shock parameters: time, density. Comparison of the molecular composition and Spectral Line Energy Distribution of various molecular species with the Paris-Durham shock code permits us to constrain the parameters of the shock and pre-shocked material.

The data taken at the telescope are openly available here

108-20 Chemical imprints of protostellar outflow shocks (SerpS-MM18)
150-19 Maps of the Sagittarius A region at 3mm and 1mm
168-14 Herbig-Haro jets in Star-Forming Regions
127-18 Outflow shocks in the Solar-type Star Forming Region L1157
125-17 Herbig-Haro Jets in Star-Forming Regions
127-16 Radiatively Driven Implosion in M20
143-15 Radiatively Driven Implosion in M20
 

The data are available as 30m files, which can be read with CLASS/GILDAS.